The Master Of Magnetics "Steven Mark"

[giantkiller]

Re: 7.8 hz toroid cals
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Quote from: giantkiller on October 11, 2006, 02:46:49 AM
Quote from: mikestocks2006 on October 11, 2006, 02:31:17 AM
yes, I had also posted something similar here for the 7.8Hz geofield frequency.

A sample toroid would be:

To get to 7.8 Hz and with use of an external capacitor
An example configuration, calculates
External C approx 39mF
Toroidal radius 10 cm
Coil radius 4 cm
Number of turns 1000
Air core

How does a poster quote a post to a message and back again? I have only been able to put 'page:xxx' in the message and then search for the page. Agh! It would be nice to take a page and post it to yourself.

--giantkiller

[giantkiller]

@jason
page  391

Guys,

I was doing some research and came across this article at http://users.netonecom.net/~swordman/Radio/re-loop-article.htm and found this to be of interest, we have been talking about tuning the collector coil to a particular frequency and this should be of help so I wanted to share this. excerpt:

Effective length (of loop antenna)

When we discussed active-antenna systems [in a prior article in the series, and which I don't have], we frequently mentioned the effective length of an antenna (often referred to as effective height). We can also talk about the effective vertical length of a loop antenna. An approximation for computing the effective length, LL, of loop antennas is

LL = (2*pi*n*A*Mu)/(wavelength) [Eq. 1]
Where wavelength is in meters; n = the number of turns in the loop; A = the cross-sectional area of one turn in square meters; Mu = the effective permeability of the core material ( = 1 for air core); and wavelength = (3*(10**)/(frequency in Hz). [That's wavelength = three times ten to the eighth power, then divided by frequency.]

Hope this is understandable.


Regards,

Carl

--giantkiller

[Jdo300]

Re: 7.8 hz toroid cals
--------------------------------------------------------------------------------
Quote from: giantkiller on October 11, 2006, 02:46:49 AM
Quote from: mikestocks2006 on October 11, 2006, 02:31:17 AM
yes, I had also posted something similar here for the 7.8Hz geofield frequency.

A sample toroid would be:

To get to 7.8 Hz and with use of an external capacitor
An example configuration, calculates
External C approx 39mF
Toroidal radius 10 cm
Coil radius 4 cm
Number of turns 1000
Air core

How does a poster quote a post to a message and back again? I have only been able to put 'page:xxx' in the message and then search for the page. Agh! It would be nice to take a page and post it to yourself.

--giantkiller

What formulas did you use to calculate this? Just the normal formula for calculating resonance of a tuned LC tank? Or is there a specific one that is for use with toroids?

Also, I should bring this up again, but concerning the segmented collector coils. What is the present belief about how the rotating field is established? So far I have heard three possible setups.

1. The coils are setup like a two-phase motor (four segments) and fed independently in pares with two 90 degree offset pulses.

2. The coils are all simply connected in series and a pulse is fed into them

3. (From anonymous poster) the coils work with transistors and are self-triggering (I just might try that if I can wire it up right).

At this point, I'm going to try option 1. Though I may build in functionality for option three if someone could give me some vague idea of how to wire the setup. I know it involves using a pickup coil to trigger the MOSFETS but that?s about all I know there. The good thing about this setup is that the frequency can actually speed up whereas with option 1, I think the frequency is just determined by the pulse rate (right?).

@Stefan,

Is the upload folder issue fixed? I will be ready to post my demo videos of the transformer experiment later this evening.

God Bless,
Jason O

[motofox]

http://video.google.co.uk/videoplay?docid=-1776848428018799270&q=genre%3ASCI_TECH

[Jdo300]

Hi giantkiller,

I do remember seeing that equation in the loop antenna link. But I think I am not using the formula correctly

LL = (2*pi*n*A*Mu*F)/(3.0*10⁸)

Okay, so LL is supposed to be the effective lengh of the loop antenna if it were straight?

Lets say that I have my collector coil made out of the Litz wire I mentioned before. If I use, say 5 loops of this wire, and I want to tune it to resonate at the 5000Hz spikes that I am pulsing into the control coils. I am shooting for the 4in diameter toroid so the area of my loop in meters comes out to be 0.008107m²; Mu is 1. So I plug it all into the formula:

(2Pi * 5 * 0.008107 * 1 * 5000) / (3.0*10⁸)

and I get 4.244*10^-6??

What does that mean? Apparently, I made a mistake somewhere that I'm not seeing. Or maybe I am using this formula completely wrong.

God Bless,
Jason O